Conductor Sharing has been used for many years on offshore platforms and it can be improved for subsea applications to reduce the cost of offshore development significantly. Oilfield Innovations have patented a bore selector arrangement that can drill multiple wells through a conventional 18 3/4 inch wellhead. Download Oilfield Innovations' White Paper to read more.
Proven conventional technology can be improved by splitting the 18 3/4 inch wellhead connector from the casing hangers so as to insert a rotatable whipstock for selecting one of the three (3) wells sharing the conductor as shown below.
A rotatable whipstock bore selector can direct drilling and casing assemblies into the desired well within the conductor being shared. Accordingly, the bottom hole assembly (BHA) from on well can be racked back prior to rotating the whipstock bore selector and running back into the hole with the same BHA to avoid time consuming and cost picking-up and laying down drill pipe and BHA components. Within stable formations, the same hole size section can be drilled for three (3) different wells followed by running casing with only one rig-up and rig-down of casing running equipment.
As shown above, proven Extended Reach Drilling Technology (ERD) allows well to be drilled thousands of feet and metres from the conductor being shared and, thus, drilling three (3) subsea wells from a single conductor to minimise expensive subsea infrastructure and pipelines can save significant cost. Drilling wells extending to three (3) miles or five (5) kilometres in any direction from a shared conductor is realistically and economically viable
A rotatable whipstock bore selector can also direct the completion of three (3) different wells sharing the same conductor and the same subsea production tree. An 18 3/4 inch subsea wellhead has sufficient space for three (3) parallel 5 1/2" tubing strings and completion jewellery to complete three different wells under a single subsea production tree.
Actuators, Valves and Remote Control Vehicle (ROV) interfaces for three (3) separate wells can be combined into a single subsea production tree, as shown above. The remaining side of the subsea production tree can be used for choke valves and an export manifold from each of the wells to the tie-back pipeline. Using a single wellhead for three (3) wells provides one pipeline and umbilical interface to reduce subsea tie-back costs to an absolute minimum.
Choke valves on each of the independent wells can be manage production to, for example, choke back wells producing too much water. Alternatively, water production and disposal costs can be managed by also using the conductor as a vertical separator.
Oilfield Innovations’ ribbed high pressure large diameter conductor-in-conductor arrangement, can provide double or triple barrier downhole subsea separation for minimum production facilities and subsea wells.
Multiple independent walls provide the barriers necessary for creating a downhole high pressure vertical production separator that can knock out and dispose of water before it enters the tie-back pipeline.
Gravity separation of heavier water, which sinks to the bottom of the separator, can premature termination of production because the hose facility cannot handle it.
Oilfield Innovations’ vertical separator can be installed within shallow geology where drilling is easier and double or triple walled high pressure large diameter conductor can be installed to, for example, a depth 330 feet (100m) to 660 feet (200m) below mud line.
The vertical separator can be hundreds of metres or feet in height, with a significant volume and residence time for gravity separation of water, which is taken from the bottom of the separator and pumped into a disposal annulus or disposal well while hydrocarbons are taken from a shallower depth and exported to the tie-back pipeline.
Alternatively, Oilfield Innovations Magic Crossover can be used or a dedicated disposal well can be placed for injecting water below the production zone for re-pressurization of the reservoir in a pseudo water flood or water-sweep scenario.
A low cost vertical separator, insulated by the subterranean strata, forming part of a well architecture where water disposal and production through heat-exchanger-like casings passing through the separator can maintain hydrocarbon exports at near reservoir temperatures could provide a dramatic step-change in offshore development.
More information can be found on our other web pages.
Conductor sharing is not only applicable to subsea developments. Conductor sharing is also applicable to minimal facility Normally Unmanned Installations (NUIs). Oilfield Innovations can provide high pressure and bending capacity conductors to install as riser or as Mono Pod jackets that can facilitate minimal facility installation with conventional jacket and topsides equipment or with a drilling rig. For example, a drilling rig could jack-up on an offshore location, set a combined Mono Pod jacket and conductor, drill the wells, set the Mono Pod Topsides and complete each of the wells while subsea hook-up and commissioning took place to minimise capital expenditure and the payback period.
Proven conventional conductor sharing wellheads exist and can be easily tied back to Oilfield Innovations' Conductor Sharing Technology.
Where water depths and sea states are appropriate, more expensive subsea tie-backs can be replaced by minimal facilities Mono Pod developments that reduce cost and maximise flexibility and access.
Why move the rig three (3) times to drill three (3) wells? Share the conductor and "Batch" drill and complete three (3) wells concurrently with one (1) rig move. Transfer learnings from one well to the next immediately by batch drilling hole sections without laying down the bottom hole assembly (BHA). Save time and money. For unconventional wells you can simultaneously frack three (3) wells at once.
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